textproduct: Quad Cities

KEY MESSAGES

- Multiple rounds of repeating storms today poses a flash flood threat, especially along and south of Interstate 80. Rain amounts between 0.5-3" likely with localized 4" totals possible.

- There is a Marginal (Level 1 of 5) Risk for severe weather today. The primary hazard with any severe storms will gusty winds.

- Drier conditions late week and into the weekend with a possible return to active weather early next week along with slightly above average temperatures.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 152 AM CDT Wed Aug 5 2026

An active Wednesday ahead! A shortwave trough is expected to dive into the base of a longwave trough over the region and help spawn widespread showers and storms (70-90% coverage) along and north of a stationary boundary draped across our southern CWA. The ingredients are there for heavy rainfall: enhanced diffluent flow aloft, PVA at 500 mb, F-gen in the 850mb-700mb layer, and 1-2 inch PWATs oriented northwest to southeast. Interstate 80 will be the dividing line for the heaviest rainfall with areas south seeing 1-3 inches across two rounds of storms (one in the morning and a second in the late afternoon/evening) while areas north could only see 0.5-1 inch mostly in the morning round. In terms of severe weather, the threat appears limited and uncertain as morning convection and cloud cover is expected to dampen diurnal heating and cut into the available energy for storms; however, areas along and south of Interstate 80 that see breaks in the clouds during the early afternoon could see some modest destabilization in the form of 500-1000 J/kg. There is greater confidence though on the 0-6 km bulk shear with a 80-100% chance for it to exceed 35 knots Wednesday afternoon along and west of the Mississippi River. With all these factors, the SPC does have a Marginal Risk (Level 1 of 5) for the areas along and south of Interstate 80 in the low CAPE, high shear environment. Primary threats will be gusty winds, lightning, and heavy rainfall, but small hail and an isolated tornado cannot be ruled out.

Heading into tonight, the shortwave trough and convection pushes the surface boundary southeastward out of our CWA as dry air advection in the mid-levels begins and high pressure builds in. Isolated showers and storms (20-30% coverage) could still continue into the overnight hours Wednesday along and south of Highway 34, but coverage should decrease by Thursday morning. Despite the frontal passage, lows will only drop into the 60s with residual surface moisture and cloud cover cutting into the radiational cooling.

Thursday will be mostly dry as surface high pressure camps over the area as the shortwave trough moves to the east. Highs are forecast to barely climb into the 80s with light and variable winds areawide. These conditions are not expected to last long though as the next shortwave dives into the Northern Plains late Thursday night, pushing another weak cold front southward into Minnesota and the Dakotas.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 152 AM CDT Wed Aug 5 2026

Friday...Isolated to scattered storms (20-40% coverage) are back on the table as a surface trough moves through the area. Limited instability due to the lack of prolonged return flow and WAA should dampen the severe threat with these storms, but the northwesterly flow aloft does put the shear vector perpendicular to the front, leaving the door open to a possible MCS development as noted in the SPC's Day 4-8 Convective Outlook. By Friday night, the boundary clears the CWA as another weak high pressure moves in.

Saturday...A rinse-and-repeat of Thursday is likely on Saturday as convergence aloft on the backside of Friday's shortwave trough and low-level CAA keep things dry. Highs and lows should be seasonable, but once again, these pleasant conditions will not last.

Sunday-Tuesday...There is a lot of uncertainty in PoPs heading into early next week as persistent west-northwesterly flow aloft prevents any significant moisture advection into the region. What is a little more certain is the shift in low-level flow. Another weak shortwave is forecast to deepen a low pressure on the leeward side of the Northern Rockies and move eastward towards Iowa and Minnesota on Monday. General consensus among ensemble models is a southerly wind shift which will kick off a warming trend Sunday and into early next week with highs likely (60-80% chance per 04.12z LREF guidance) in the mid-80s to low 90s. Any residual boundary left across the region on Tuesday will also play a huge role on the northward expansion of the heat.

AVIATION /06Z TAFS THROUGH 06Z THURSDAY/

Issued at 152 AM CDT Wed Aug 5 2026

On-and-off showers and thunderstorms are likely (60-90% chance) late tonight through Wednesday afternoon. Between lowering cloud ceilings for CID/DBQ and lower visibility with heavy rainfall at MLI/BRL, MVFR to IFR conditions are on the table (50-70% chance for CID/DBQ, 30-50% for MLI, and 20-30% for BRL) with TSRA possible at all sites. Two rounds appear likely with greatest coverage during 10-14 UTC and 18-22 UTC. In terms of wind, there is a low chance (10-20%) for gusts over 20 knots at CID/DBQ and a little higher for MLI/BRL at 30-60%. Lack of consensus between models lead to the exclusion of gusts from the MLI/BRL TAFs.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.